This application claims the priority of German Patent Document 100 49 194.4, filed in Germany, Oct. 5, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a reactor structure as a heat exchanger layer stacking construction. Preferred embodiments relate to a reactor structure as a heat transfer layer stacking construction having a stack of heat-conductive plate elements which, alternating in the stacking direction, bound one reactor layer respectively, which is filled with a reaction catalyst material for catalyzing a chemical reaction, and one tempering layer respectively, through which a tempering medium can flow, adjacent plate elements being connected in a fluid-tight manner on at least two closed side areas. Such a reactor is suitable, for example, for being used as a reforming reactor for generating hydrogen in a fuel cell vehicle or in stationary fuel cell applications by reforming methanol or another applied substance.
This type of a reactor structure is disclosed in German Published Patent Application DE 44 20 752 A1. There, only the catalyst material filling them is charged into the reactor layers which have a larger volume, while the heat-conducting corrugated ribs are inserted into the tempering layers, which have a smaller volume, and in that case specifically are heating layers. In a different embodiment illustrated there, the reactor layers are not filled with a catalyst material but the facing sides of the plate elements are provided with a corresponding catalyst coating and supporting or flow-conducting corrugated ribs are inserted in the reactor layers as well as in the heating layers.
The invention is based on a technical problem of providing a reactor structure of the initially mentioned type which can be manufactured at relatively low expenditures in a compact and pressure-resistant form while it provides reactor layers which have a volume as large as possible, which reactor layers can be tempered to be maintained at a desired temperature by way of tempering layers situated in-between the reactor layers, and which reactor structure is particularly suitable for generating hydrogen for feeding a fuel cell system, for example, in a fuel cell vehicle.
Preferred embodiments of the invention solve this problem by structure arrangements that provide for reactor layers with a larger height than the tempering layers.
Special plate elements are used for the reactor structure according to certain preferred embodiments which on at least two non-adjacent side areas along which they are connected in a fluid-tight manner with one adjacent plate element respectively for forming a closed lateral area, extend in a U-shaped bent manner and are arranged with their U-side flanks resting against one another in the stack such that the reactor layers have a greater height than the tempering layers. By using the laterally appropriately bent plate elements, no separate lateral spacer elements are required for building up the layer stack. Simultaneously, the lateral U-shape is selected such that adjacent plate elements can be reliably connected with one another along their mutually facing U-side flanks and thus in a flat manner and not only in a linear shape in a fluid-tight manner. In addition, with respect to the tempering layers, clearly higher and thus larger-volume reactor layers can be formed, which in the case of a given, desired reactor conversion performance promotes a compact structural shape of the reactor structure.
Also in the case of the reactor structure according to certain preferred embodiments of the invention, such a compact structural shape can be achieved with larger-volume reactor layers and smaller-volume tempering layers. In addition, heat-conducting corrugated ribs are inserted into the reactor layers, which corrugated ribs, on the one hand, promote the heat transfer between the reactor layers and the tempering layers and the heat distribution within the reactor layers and, on the other hand, can be used as a supporting structure for the larger-volume reactor layers, which can improve the stability and the pressure resistance of the layer stacking construction. This measure can preferably be combined with the use of plate elements with lateral areas extending in a manner bent in a U-shape.
In a further development of certain preferred embodiments of the invention, essentially plane plate elements are used which are appropriately bent in a U-shaped at the corresponding lateral areas, so that, as a result, when the plate elements are joined together, lower tempering layers and higher reactor layers are alternatingly formed.
In a further development of certain preferred embodiments of the invention, plate elements of a corrugated structure are used for the reactor structure. In comparison to plane plate elements, while the base surface is the same, this results in a larger heat-transfer-active contact surface between the reactor layer and the heating layer.
In the case of a reactor structure further developed according to certain preferred embodiments of the invention, corrugated ribs are also provided in the tempering layers, which further contributes to the stability of the layer stacking construction and can improve the heat transfer characteristics.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.